This application claims priority to United Kingdom Application No. 9919671.9 filed Aug. 20, 1999 and assigned to Markem Technologies Ltd., the entire contents of which is incorporated herein by reference.
This invention relates to a method of handling a lamina object. More particularly but not exclusively the method relates to a method of handling a label, e.g. for conveying a self adhesive label when removed from a backing web to which the label was releasably adhered, to a position from where the label may be applied to an article.
Apparatus are known for applying labels to articles using a blast of air applied through small holes in an applicator plate. The labels are held in contact with the plate by suction, which suction is overcome by or released while, the blast of air is applied.
From for example, U.S. Pat. No. 4,255,220 it is known to move such applicator plate to convey a label on the applicator plate from a position where the label is removed from a backing web, to a position where the label is applied by a blast of air. In common with other known similar arrangements, this therefore requires a drive and transmission means to move the applicator plate under the control of a control means which must also synchronise the application of a blast of air to remove the label from the applicator plate for application to an article, at an appropriate time.
According to one aspect of the invention we provide a method of handling a lamina object including feeding the lamina object on to surface of a handling member, the surface of the handling member including a plurality of first openings connectable to a vacuum source sufficient to attract the object to the member, and a plurality of second openings connectable to a source of pressurized gas, the method including applying suction to the first openings and simultaneously applying pressurized gas to the second openings, the suction and pressurized gas being controlled to lift the object out of direct contact with the surface of the handling member whilst retaining the object close to the surface, and applying a directed jet of pressurized gas to move the object relative to the handling member across the surface of the handling member.
Thus utilising the present invention, a lamina object such as a label may be conveyed without moving the label handling member.
In a preferred arrangement, the first openings in the surface of the handling member are arranged in a matrix which extends over substantially the entire surface of the handling member. The matrix may include a plurality of rows and columns. The second openings may too be arranged in a matrix over the surface of the handling member, the second openings being provided in lands between the first openings.
The first openings may all be connected to a common plenum so that the method includes providing a substantially constant vacuum over the surface of the handling member.
The second openings may be arranged in groups, each group being connected to a plenum which provides pressurized gas to the second openings of that group only. Preferably the second openings of the group are arranged in a zone of the surface of the handling member, and the method may include applying a greater gas pressure to the second openings of one group at an instant, compared to another group.
The method may include applying pressurized gas to the second openings of one group in one zone only prior to or subsequent to moving the object over the surface of the handling member so that the object may be retained in the zone to which gas pressure is applied or is not applied.
Thus where the handling member dimensions are sufficient for a plurality of objects to be fed on to the surface of the handling member, the plurality of objects may independently simultaneously be handled in different zones.
Where there are a plurality of zones arranged in a conveying direction, it has been found that by not applying pressurized gas to one of the zones, an object may be conveyed across the surface of the handling member by the directed jet, to a position where the zone to which the pressurized gas is applied meets an adjacent zone where only suction is applied, and may be held substantially stationary in that position until pressurized gas is applied to the second openings of the adjacent zone, or alternatively the object may be held substantially stationary within a zone, by temporarily discontinuing to supply pressurized gas to at least that zone.
Where there are a plurality of zones arranged laterally of a conveying direction, a corresponding plurality of objects may be moved across the surface of the receiving member substantially simultaneously and independently.
Although the surface of the handling member may be generally horizontal, the invention may be practiced where the surface is inclined to the horizontal or is even upside down. Where the surface is substantially upright, the method may include directing jets of pressurized gas in a direction to counter the effects of gravity. Alternatively, the method may include providing a runner along the bottom edge of the surface of the receiving member to prevent gravitational force acting on the object to cause the object to fall from the surface.
In a preferred embodiment a plurality of the second openings may each provide a directed jet to direct the object across the surface of the handling member although one or more directive jets may be provided which are not provided in the handling surface, if desired.
The method may include controlling the flow of pressurized gas to the second openings of the zones so that pressurized gas at a first pressure is fed to one zone and pressurized gas at a second pressure is fed to another zone in such manner that the orientation of the object on the surface of the handling ember may be changed in a controlled manner. For example in the case of a label, the label may be dispensed onto the surface of the handling member in one orientation, and rotated as the label moves across the surface of the handling member, so that the label may subsequently be applied to an article in an alternative orientation different from its orientation as the label was dispensed on to the surface of the handling member.
The invention is particularly useful for handling a self adhesive label or labels, in which case the method may include removing the label from a backing web prior to feeding the label on to the surface of the handling member. Such removal may be achieved using a peel bar for example.
The method may further include applying the label to an article which is moving relative to the handling member. This may be achieved by directing the label from the surface of the handling member and wiping or rolling the label onto the relatively moving article.
According to a second aspect of the invention we provide an apparatus for performing the method of the first aspect of the invention, the apparatus including a handling member having a surface including a plurality of first openings connected in use to a vacuum source sufficient to attract the object to the member, and a plurality of second openings connected in use to a source of pressurized gas so that suction and pressurized gas are simultaneously applied to the surface of the handling member, means to control the suction and pressurized gas to lift the object out of direct contact with the surface of the handling member whilst retaining the object close to the surface, and there being means to apply a directed jet of pressurized gas to move the object relative to the handling member across the surface of the handling member.
Typically the label is lifted from the surface of the handling member only a very small amount, e.g. less then 0.5 mm. Thus as the label moves, there is the possibility of a part of the label coming into contact with the surface.
Thus the surface of the handling member may be a lubricated surface to aid label movement over the surface. For example the surface may be coated with or even made from a dry lubricant such as polytetrafluoroethylene.
The cross sections of at least some of the second openings may locally be enlarged at the surface of the handling member, and may include a flow passage which is inclined relative to surface, thus to provide directed jets.